I'm currently trying to make a change to my schedule, which involves switching quiz sections in a class I'm already registered in, in order to make room for a class that would overlap. I asked my professor about it because the needed quiz section is full, and he said he'd send me an add code. It's relatively time sensitive, and he's normally super fast getting back to emails (his initial response came in within a few minutes of my first email and I responded almost immediately) but we discussed it mid-day yesterday and I still haven't received an add code from him. I don't want to be rude and over-do it with the emails, but I don't want to risk going the whole weekend without resolution if he's not a weekend email person.

How long do y'all think it's acceptable to wait before sending a follow up on something like this? I'm kinda hoping for a LOR from this professor because I think he'd be a good person to ask for one from, so I want to make sure I don't make a weird impression.